Regulation of ENaC expression at the cell surface by Rab11.
The epithelial Na(+) channel (ENaC) is an essential channel responsible for Na(+) reabsorption. Coexpression of Rab11a and Rab3a small G proteins with ENaC results in a significant increase in channel activity. In contrast, coexpression of Rab5, Rab27a, and Arf-1 had no effect or slightly decreased ENaC activity. Inhibition of MEK with PD98059, Rho-kinase with Y27632 or PI3-kinase with LY294002 had no effect on ENaC activity in Rab11a-transfected CHO cells. Fluorescence imaging methods demonstrate that Rab11a colocalized with ENaC. Rab11a increases ENaC activity in an additive manner with dominant-negative dynamin, which is a GTPase responsible for endocytosis. Brefeldin A, an inhibitor of intracellular protein translocation, blocked the stimulatory action of Rab11a on ENaC activity. We conclude that ENaC channels, present on the apical plasma membrane, are being exchanged with channels from the intracellular pool in a Rab11-dependent manner.
Karpushev
Alexey V
AV
Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Levchenko
Vladislav
V
Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Pavlov
Tengis S
TS
Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Lam
Vy
V
Biotechnology & Bioengineering Center, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Vinnakota
Kalyan C
KC
Biotechnology & Bioengineering Center, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Vandewalle
Alain
A
INSERM, U773, Centre de Recherche Biomedicale Bichat-Beaujon CRB3, Universite Paris, Paris, France.
Wakatsuki
Tetsuro
T
Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA; Biotechnology & Bioengineering Center, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Staruschenko
Alexander
A
Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA; Kidney Disease Center, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA. Electronic address: Staruschenko@mcw.edu.
D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D051379:Mice; D014162:Transfection; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020826:rab3A GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D000099193:rab11 GTP-Binding Proteins
D053503:Epithelial Sodium Channels; D020691:rab GTP-Binding Proteins; D020826:rab3A GTP-Binding Protein; D000099193:rab11 GTP-Binding Proteins